Forming die structure

ABSTRACT

A FORMING DIE HAVING A BASE MMBER AND AN ELONGATED FORMING MEMBER SECURED TO THE BASE MEMBER, THE FORMING MEMBER HAVING AN INNER SURFACE, AN OUTER SURFACE AND A CONNECTING SHEET CONTACTING SURFACE. THE FORMING MEMBER DEFINES AN ELONGATED RECESS DISPOSED GENERALLY AT THE INTERSECTION OF THE INNER SUFACE AND THE SHEET CONTACTING SURFACE. A CYLINDRICAL ROLLER WHICH IS ROTATABLY SUPPORTED IS DISPOSED WITHIN THE RECESS. IN ONE FORM THE DIE IS PARTICULARLY SUITED TO BENDING DECORATED SHEET WITHOUT CREATING SURFACE DAMAGE. IT HAS TWO SPACED PARALLEL FORMING MEMBERS SECURED TO THE BASE MEMBER IN CHANNEL DEFINING POSITION. THE FORMING DIE MAY HAVE THE ROLLERS IN CONTACT WITH THE FORMING MEMBER WITHIN THE GENERALLY CYLINDRICAL RECESS OR MAY HAVE UNITARY OR SEGMENTED SPACER MEANS INTERPOSED BETWEEN THE ROLLERS AND THE FORMING MEMBER. THE SPACER MEANS HAS A CONCAVE SURFACE OF SUBSTANTIALLY THE SAME RADIUS OF CURVATURE AS THE ROLLER, IN CONTACT WITH THE ROLLER.

on. 19, 1971 R. c. HADDON 3, 1

- FORMING DIE STRUCTURE Filed April 28, 1969 2 Sheets-Sheet 1 30 FIG. 30y FIG. 20.

' FIG. 3.

INVEN TOR.

' l8 ROGER C. HADDON wamm Affarney zsheets -sheet 2 R- C. HADDQN FORMINGDIE STRUCTURE FIG. 5.

Oct. 19, 1971 Filed April 28. 1969 FIG. 7.

I02 I04 I02 United States Patent O "ice 3,613,427 FORMING DIE STRUCTURERoger C..I-Iaddon, Pittsburgh, Pa., assignor t Aluminum Company ofAmerica, Pittsburgh, Pa. Filed Apr. 28, 1969, Ser. No. 819,850 Int. Cl.B21d 9/10 US. Cl. 72212 Claims ABSTRACT OF THE DISCLOSURE A forming diehaving a base member and an elongated forming member secured to the basemember, the forming member having an inner surface, an outer surface anda connecting sheet contacting surface. The forming member defines anelongated recess disposed generally at the intersection of the innersurface and the sheet contacting surface. A cylindrical roller which isrotatably supported is disposed within the recess. In one form the dieis particularly suited to bending decorated sheet without creatingsurface damage. It has two spaced parallel forming members secured tothe base member in channel defining position. The forming die may havethe rollers in contact with the forming member within the generallycylindrical recess or may have unitary or segmented spacer meansinterposed between the rollers and the forming member. The spacer meanshas a concave surface of substantially the same radius of curvature asthe roller, in contact with the roller.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to forming die structures and more specifically to diestructures uniquely adapted to form metal sheet while avoiding damage todecorative surfaces thereof.

Description of the prior art One of the problems encountered in formingmetal sheet by means of a complementary die and punch is that ofavoiding surface damage to the sheet. While the problem is troublesomewith respect to forming of any sheet material, this problem isparticularly acute when the sheet being worked upon is a decorated orpatterned sheet and the forming is effected solely or to a substantialextent by bending. The problem is present regardless of whether thebending operation is a single bending stage or a multiple bend.

As such surface damage contributes substantially to waste throughrejection of the ultimate product, various means of minimizing thisproblem have been employed. It is known to attempt to reduce suchsurface dam age by use of dies made of rubber. As these dies have anextremely short die life as compared with dies made from moreconventional material such as tool steel, the increase in cost ofreplacement is substantial.

It has also been known to attempt to minimize damage to the sheetsurface by employing various types of lubricants. While such an approachtends to be helpful, it is frequently imprecise and results in a lack ofproduct uniformity. Also, additional attention of workmen must bedirected toward the provision of an adequate amount of lubricant.

It has also been known to periodically refinish the die radius in orderto remove irregularities which contribute to undesired surface defects.This form of continuous maintenance not only requires periodic shutdownof a fabricating line, but also requires the expense of the laborinvolved in refinishing the die.

US. Pat. 2,908,315 suggests the use of large floating 3,613,427 PatentedOct. 19, 1971 rollers disposed within V-shaped grooves in a sheetbending operation. A punch cooperates with the tworollers to establish achannel shaped bend in the metal sheet. It is noted that a minimum ofscratching of the sheet will occur as the relative movement between thesheet and female die is reduced through the use of rollers. As therollers employed in this patent are retained in operating positionsolely by gravity, the female die contemplated by the inventiondescribed in that patent could be employed only in a horizontal upwardlyopen position. Also, in view of the nature of the fit between therollers and the grooves, a region for undesirable accumulation andentrapment of metal particles and other foreign materials is providedunderneath the rollers. This material may readily be transferred fromthe rollers to the workpiece or create a surface defect therein throughcontact with the foreign material on the rollers. One additionaldisadvantage of the system disclosed in this patent is the need tosubstitute rollers each time a change in product configuration iscontemplated. A further disadvantage of the system disclosed in US. Pat.2,908,315 is that by establishing a given diameter of roller, one alsofreezes the flexibility with respect to depth of member which may beformed.

SUMMARY OF THE INVENTION The above enumerated problems have been solvedby the die structure of this invention. The die structure of thisinvention provides a base member and one or more upstanding formingmembers secured to the base member. Each forming member has an innersurface, an outer surface and a connecting sheet contacting surface. Theforming member defines an elongated recess which is disposed generallyat the intersection of the inner surface and sheet contacting surface. Acylindrical roller is rotatably supported within the recess.

In the embodiment of the invention wherein a single forming member isprovided the die may be effectively employed in cooperation with asuitable punch to perform wiping or single bend operations on a sheet.

In embodiments of the invention employing two forming members they maybe disposed in parallel spaced relationship to cooperate vwth the basemember in defining a channel shaped die structure suitable for formingsimultaneous double bends in a sheet. As the height of the formingmember may be determined independently of the diameter of the rollers,the depth of bend may be readily established independent of the rollerdiameter.

In one form of the invention the recess in the forming member is ofcomplementary configuration to the roller and is in contact therewith.This contact provides a cleansing or wiping action to the roller andprevents pick-up of foreign materials which are potentially damaging tothe sheet surface. An alternative structure contemplated by thisinvention provides a roller retaining insert or spacer which is receivedwithin the elongated recess of the form ing member and has acomplementary concave surface in contact with the roller. This spacer ispreferably made from a material having a lower coeflicient of frictionthan the forming member. This serves to increase the freedom of rotationof the roller.

In another form of the invention, the roller receiving spacer may be aplurality of spacer elements positioned within the recess at spacedintervals. A suitable filler material may be positioned in the gapsbetween spacer elements.

It is an object of this invention to provide a sheet forming die havingroller elements rotatably secured thereto in such a manner as to resistscratching or defacing of the sheet surface during the formingoperation.

It is another object of this invention to provide a bending diestructure which is so designed as to resist accumulation of dirt at anysheet contacting roller posi tion and also to provide positive rollercleaning means to continuously remove any foreign material depositedupon the roller.

It is another object of this invention to provide a bending die adaptedfor variations in width or depth of a multiple bend without requiringalteration of roller size.

It is another object of the invention to provide a sheet metal bendingdie having relatively small roller members secured to the die in such amanner as to permit free rotation thereof and so structured as to reducethe likelihood of galling of the rollers.

These and other objects of the invention will be more fully understoodand appreciated from the following detailed description of the inventionon reference to the illustrations appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of one form ofdie structure contemplated by this invention.

FIG. 2 is a sectional elevational view of the die illustrated in FIG. 1,taken through 22, showing also a metal sheet and complementary punch.

FIG. 2a illustrates an enlarged detailed representation of the encircledportion of FIG. 2.

FIG. 3 is a sectional elevation illustrating the die structure of FIG. 2with the metal in an intermediate stage of bending.

FIG. 4 is a sectional elevation of a modified form of die structure ofthis invention showing the sheet in the final bending stages.

FIG. 5 illustrates a sectional elevation of another embodiment of thisinvention showing a die member employed in a wiping or single bendoperation.

FIGS. 6 and 7 illustrate top plan sectional views showing embodiments ofthe invention employing segmented roller receiving or spacer elements.

FIG. 8 illustrates a sectional elevational view of a modified form ofspacer member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specificallyto the drawings, with particular reference to FIGS. 1 and 2, there isillustrated a die structure having a base member 2 with a pair offorming members 4 secured to the base member 2 and upstanding therefrom.The forming members 4, in the form illustrated, are disposed generallyperpendicular to the base member 2 and are positioned in parallel spacedrelationship with respect to each other. The forming members 4 each havean inner surface 6, an outer surface 8 and a connecting sheet contactingsurface 10. The forming members each have a generally cylindrical recess defining wall 16 disposed generally at the intersection of innersurface 6 and connecting sheet contacting surface 10.

The forming members 4 cooperate with the base member 2 to define agenerally channel shaped die opening 18. The recess defining walls 16are positioned in overlying spaced relationship with respect to the basemember 2 and are disposed on opposed sides of the entrance to the dieopening 18.

A substantially cylindrical roller member 20 is received within therecess defined by wall 16. In the form illustrated, a spacer member 22is interposed between wall 16 and roller 20. Both the roller 20 and thespacer member 22 are continuous and substantially coextensive with therecess defined by wall 16. The spacer member has a concave surface 24 ofsubstantially the same diameter as the roller 20 which is insubstantially continuous contact with the roller 20 over a substantialportion of the roller surface. it is generally preferred that thiscontact exist over approximately /2 or a major portion of the rollercircumference. The spacer member 22 also has a convex surface in contactwith wall 16.

As is shown in FIG. I, opposed ends of rollers are rotatably journaledwithin openings in end walls or plates 32. The rollers are, therefore,positioned in the entrance to die opening 18, are secured to the formingmember 4 but are journaled for free rotation therein. As is shown inFIG. 2a the contact between roller 20 and spacer 22 is such that nomeaningful voids which could facilitate the accumulation of metalparticles or other potentially harmful foreign materials are present.This not only reduces the likelihood of galling of the rollers throughcontact with such materials, but also reduces the likelihood ofimpairment of the surface characteristics of the metal sheet beingformed. As a result of the freedom of rotation provided at the entranceto die opening 18, the metal being moved over the rollers 20 issubjected to rolling frictional contact with the roller rather thansliding frictional contact with a rigid die portion. This reduced forcealso contributes to the reduced likelihood of sheet or die surfacedamage.

Another feature of this invention, as is illustrated in FIG. 2a, is theprovision of a roller wiping or cleaning structure. Insert or spacer 22,in the form illustrated, contacts the roller 20 substantiallycontinuously within the recess between initial contact point 34 andterminal contact point 36 along surface 24. Any dirt which might bepicked up on the exposed surface 38 of roller 20 will upon continuedrotation of the roller 20 be brought into contact with initial contactpoint 34 which will restrain the dirt particles against continuedmovement with the roller and will thereby provide a wiping action whichfrees the dirt from the roller. Terminal contact point 36 prevents entryof air-borne materials into the space between the roller and the spacermember 22.

In the emobdiment shown in FIG. 4 a slightly different form of rollerdie structure is illustrated. The roller 20 is in direct contact withthe recess defining wall 16 of forming member 4. (For clarity ofillustration, a slight space between roller 20 and wall 16 has beenshown.) The configuration of wall 16 is complementary with respect tothe surface of roller 20 with contact being substantially continuouslymaintained from initial contact point 40 through terminal contact point42. While this form eliminates the need for use of spacing member 22,this benefit is somewhat reduced by the need for more precise machiningof wall 16.

Another form of die assembly is shown in FIG. 8 wherein roller 20 isreceived within spacer member 50. Forming member 4 has a generallyrectangular recess defined by surfaces 52, 54. A complementaryrectangular surface is provided in spacer member 50. Spacer member alsohas a curved surface 56 in substantially continuous contact with roller20. By employing this configuration in spacer member 50 the amount ofprecision machining required to establish a roller receiving recesswithin forming member 4 is greatly reduced.

Referring now more specifically to FIGS. 2 through 4, it is seen that asheet or plate 60 is positioned on sheet contacting surface 10 offorming members 4. While it will be appreciated that the die of thisinvention may be employed with sheet material of various gaugesincluding foil, sheet and plate, for simplicity of disclosure, referencewill be made herein to the sheet contacting surface. A punch 62 ispositioned on the opposite side of the sheet from the forming member 4.FIG. 2 illustrates the apparatus prior to the initiation of bending,FIG. 3

shows an intermediate stage with a portion of sheet m0ving over therollers 20 as the punch 62 moves into the die opening 18 and FIG. 4shows the punch, die and formed sheet in a final forming position.

Referring now to FIG. 5, another form of the die of this invention isillustrated. In this form of the invention a female die is disposed inoverlying relationship with respect to a punch 72 and a sheet 74 isinterposed. The original position of forming member 76, which is securedto press crossbeam 82, and sheet end 74a are illustrated by the dottedline. The final position of the forming member 76 and sheet end 74a areillustrated by a solid line. In this form of the invention a singleforming element is provided in order to form a single bend by wiping endportion 74a of sheet 74 downwardly. This may be accomplished by movingthe forming member 76 downwardly While restraining the underlying punchagainst movement.

It is noted that in this form of the invention the roller 78 extendsinwardly toward the sheet 74 a distance R greater than the inner surface80 of forming member 76. In general, the exposed surface 84 of roller 78will terminate in relatively close proximity to the planes of one orboth of inner surface 80 and sheet contacting surface 86. It ispreferable, however, in order to minimize the likelihood of damagingcontact between the sheet and surfaces 80, 86 to so position the rollerthat it extends outwardly beyond one or both of surfaces 80, 86 by afinite distance.

In connection with the spacer member 22 it is preferable to have alongitudinally continuous member which is coextensive in length with therecess in forming member 4 and is also continuous in a transversedirection and coextensive with recess defining wall 16. This spacermember 22 serves to maintain the roller 20 in non-contacting positionwith respect to wall 16. This reduces the likelihood of wear of wall 16of forming member 4 through moving contact with roller 20. Also, thespacer member may advantageously be manufactured from a material havinga reduced coeflicient of rolling friction with respect to the roller 20with the material of the forming member. The reduced coefficient offriction provides for increased free rotation of the rollers andimproved performance thereof. One of the preferred materials for suchuse is Teflon which has the desired hardness and lubricating properties.A number of other suitable plastic materials may also be advantageouslyemployed. Another suitable material is a plastic filled with particlesof molybdenum disulfide. To provide effective contact with the rollerthe circumferential extent of contact between the spacer member 22 androller 20 is preferably about 180 or more. The transverse extent ofspacer member contact will, therefore, preferably be over a majorportion of the roller.

It will be appreicated that the freedom of rotation of the rollers maybe improved even more by employing segmented spacer elements 90, as isshown in FIG. 6. These elements reduce the amount of surface to surfacecontact with roller 20. In the form illustrated in FIG. 6 the elements90 which are of substantially the same circumferential extent as spacermember 22 are secured within inwardly directed curved embossmentstransversely positioned on the recess defining wall 16. In order tomaintain the self-cleaning feature of this invention it is preferred toemploy a filler material 96 in the intervals disposed between the spacerelements 90. This material 96 prevents entry of foreign materials intothe recess. Any suitable material such as felt for example, may beemployed for this purpose. As is also shown in FIG. 6, the roller 20 hasa necked-in terminal extension 98 which is rotatably secured withinbearing 109 which in turn is supported in an opening in end wall orplate 32.

Another form of segmented spacing elements 102 is illustrated in FIG. 7.In this form the spacing elements 102 are positioned within curvedrecesses transversely positioned in surface 16. This results in gaps 104of reduced size as compared to those shown in FIG. 6. In thisillustration no filler material is provided in gaps 104.

The rollers of this invention will generally be made of hardened andground steel which may, if desired, be provided with a suitableprotective coating. As the rollers will be inserted into the die at aposition where a rigid die would normally have a radius, the rollerswill generally be relatively small. A preferred size for most bendingdies is about to 1 inch in diameter.

In conventional generally channel shaped bending dies, it is customaryto provide for adjustability of the width of channel opening 18. Oneconventional means of accomplishing this is by employing shims (notshown) disposed at the exterior of inner surface 6. While the formingmemher in the forms illustrated herein has been shown as a generallysolid member, it will be appreciated that it may be assembled from anumber of elements, some of which may be shim elements adapted to beremoved or inserted in order to adjust the width of channel opening 18.It will be appreciated that the roller assembly of this invention isadapted for use with such adjustable dies, without requiring removal orsubstitution of roller members. This adjustment may, therefore, beeffected independently of the structure of this invention which iscompatible with such adjustment.

The roller assembly of this invention is such that the depth of formingor bending which may be effected within a given die is not directlyrelated to the roller diameter. It is, therefore, another advantage ofthis invention that either the diameter of the rollers or the depth ofchannel opening 18 may be altered independently of each other.

It will be appreciated that the die structure of this invention may beadvantageously employed with dies for various types of forming ofvarious types of sheet including undecorated sheet, textured sheet orsheet which has a decorative coating or film as provided by painting,anodizing or lamination. The rollers are rotatably secured within arecess in the die. The die structure is so configurated as to resistentry of dirt, metal particles and other foreign materials into theregion between the roller and the forming member. In addition,structural means are provided to cleanse the roller by wiping as itrotates to thereby remove foreign particles therefrom. This results inresistance to galling of the roller as well as surface damage to thesheet being formed.

The roller assembly of this invention may advantageously be providedwith an underlying spacer member which increases the rotational freedomof the roller and effects positive wiping action to remove dirt from theroller surface. In addition, the use of such a structure reduces theamount of precision machining which must be accomplished in order toprovide the elongated recess in the forming members. These spacers maybe both longitudinally and transversely continuous or may be provided inthe form of segmented spacer elements. The rollers are positioned withinthe recess and preferably project inwardly a slight distance beyond thenormal radius of curvature of the die in order to reduce the likelihoodof potentially destructive contact between the sheet surface andstationary portions of the forming member. In addition, the diestructure of this invention substitutes the reduced rolling frictionalforce for sliding frictional force and thereby facilitates ease offorming. This feature also serves to reduce the tension placed upon thesheet during bending and thereby reduces the likelihood of tensilefailure of the sheet. In addition, this invention may be employed with asingle forming element to form a single bend or two or more formingelements.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be apparent to those skilledin the art that numerous variations of the details may be made withoutdeparting from the invention as defined in the appended claims.

What is claimed is:

1. A sheet forming die comprising:

a base member,

said die is a bending die,

an elongated forming member secured to said base member, said formingmember having an inner surface, an outer surface and a connecting sheetcontacting surface,

said forming member defining an elongated recess disposed generally atthe intersection of said inner sur face and said sheet contactingsurface,

a single cylindrical roller disposed within said recess,

fixed spacer means disposed within each said recess intermediate saidforming member and said cylindrical roller to retain the working surfaceof said roller in non-contacting position with respect to said formingmember,

support means rotatably securing said roller within said recess,

said die having two said forming members secured to said base member,

Said support means having journals disposed at opposite ends of eachsaid roller,

said forming members extending upwardly from said base member inparallel spaced relationship with respect to each other to define agenerally channel shaped die with said rollers disposed at the entrancein spaced overlying relationship with respect to said base member,

each said elongated recess being of generally cylindrical configuration,

said inner surface disposed at substantially right angles with respectto said sheet contacting surface,

said rollers having a diameter of about to 1 inch,

said spacer means having a plurality of back-u elements disposed withinsaid recess at spaced intervals along the length of said recess, and

each said back-up element disposed in substantially continuous contactwith a transverse section of the surface of said roller and extendingcircumferentially over at least a major portion of said section.

2. The bending die of claim 1 including:

felt filler members disposed within said recess at the spaced intervalsbetween said back-up elements.

3. A sheet forming bending die comprising:

a base member,

an elongated forming member secured to said base member,

said forming member having an inner surface, an outer surface and aconnecting sheet contacting surface,

said forming member defining an elongated recess disposed generally atthe intersection of said inner surface and said sheet contactingsurface,

a single cylindrical roller disposed within said recess,

fixed spacer means disposed within each said recess intermediate saidforming member and said cylindrical roller to retain the working surfaceof said roller in non-contacting position with respect to said formingmember,

said inner surface disposed at substantially right angles with respectto said sheet contacting surface,

said spacer means having an elongated friction reducing back-up memberprovided with a concave roller contacting surface having substantiallythe same radius of curvature as said roller,

said support means having journals disposed at opposed ends of saidroller,

said back-up member being substantially continuous and longitudinallycoextensive with said recess,

said back-up member is in substantially continuous longitudinalcontacting position with respect to said roller within said recess, and

said substantially continuous contact between said backup member andsaid roller includes a circumferential arc of said roller of greaterthan 180 but less than 360, whereby said roller is rotatably securedwithin said recess in said back-up member and is retained in surface tosurface contact therewith while having an exposed forming surface.

4. The sheet forming die of claim 3 including:

said die having two said forming members secured to said base member,

said forming members extending upwardly from said base member inparallel spaced relationship with respect to each other to define agenerally channel shaped die with said rollers disposed at the entrancein spaced overlying relationship with respect to said base member, and

each said elongated recess being of generally cylindrical configuration.

5. The sheet forming die of claim 4 including said back-up member iscomposed of Teflon, and

said rollers have a diameter of about /8 to 1 inch.

References Cited UNITED STATES PATENTS 2,647,552 8/1953 Magnuson et al72-213 3,457,759 7/1969 Doerr et a1 72212 FOREIGN PATENTS 1,167,6404/1964 Germany 72-386 978,861 12/1964 Great Britain 72386 580,506 8/1958Italy 72386 OTHER REFERENCES The Tool Engineer; Press Brake Design forMagnesium by Alfred E. Blatter; vol. 34, No. 6; June 1955, p.

RICHARD J. HERBST, Primary Examiner US. Cl. X.R.

